1. Field of the Invention
The present invention relates to an image capture apparatus having a shake correction device or camera shake correctional function and, more particularly, to a technique for improving the performance of the camera shake correctional function.
2. Description of the Related Art
As recent image capture apparatuses such as a digital camera are decreasing the size and weight while increasing the zoom ratio, the influence of a camera shake is becoming serious. To solve this, a growing number of image capture apparatuses have a camera shake correctional function.
The camera shake correctional functions are roughly divided into two types, which are generally called optical camera shake correction and electronic camera shake correction. Most camera shake correctional functions of these two types detect a shake using a camera shake detection sensor. In contrast, an ultra-compact, lightweight image sensing device incorporated in a cell phone or the like often detects a motion vector from the difference between images sensed by an image sensing unit and calculates the shake amount.
In optical camera shake correction, the shake is corrected by moving a shift lens or image sensor in a direction in which the detected shake amount is canceled. In electronic camera shake correction, the shake is corrected by performing image processing to cancel the calculated shake amount.
Recently, digital cameras with a bending optical system have been developed for higher zoom ratios and lower profiles. To implement optical camera shake correction in such a digital camera, a compact, low-profile optical shift unit has been developed (Japanese Patent Laid-Open No. 2007-240736).
However, in the technique disclosed in Japanese Patent Laid-Open No. 2007-240736, a large offset is generated between the center of gravity of a movable member unit such as a shift lens and the center of action of a driving force by an actuator. A rotation moment is generated on the movable member depending on the magnitude of force. The rotation moment drives the movable member in an axial direction perpendicular to the axis of action of the driving force by the actuator. This results in an error (crosstalk) between a driving position designated by the actuator and an actual movable member position. The crosstalk may cause image blurring.